Existing electronic commerce applications allow users to make purchases of various types of information-related products over computer networks such as the Internet. For example, a user can typically purchase a software package over the Internet by accessing a corresponding web site, providing the necessary payment information, e.g., a valid credit card number, and downloading the software from the site. In such applications, the software may be transmitted to the user in an at least partially-encrypted format, so as to prevent unauthorized distribution and use of the software. An authorized user is then subsequently provided with a decryption “key” which allows the software to be decrypted and used. Similar techniques may be used to purchase and download music or other audio information, e.g., “singles,” compilations such as compact disks (CDs), live broadcasts, interviews, talking books, etc. over the Internet. A well-known conventional format for downloadable audio information of this type is the MPEG-1 Level 3 Digital Audi Standard, also referred to as MP3.
A significant problem with the above-noted conventional techniques as applied to the transfer of music or other audio information to authorized users is that it can often take an unduly long amount of time to download such information over existing networks. Moreover, the music is in many cases already delivered repeatedly to the same users over other channels, e.g., through broadcast air waves.
For example, proposed systems for providing digital audio broadcasting (DAB) in the FM radio band are expected to provide near CD-quality audio, data services, and more robust coverage than existing analog FM transmissions. However, until such time as a transition to all-digital DAB can be achieved, many broadcasters are expected to utilize an intermediate solution in which the analog and digital signals can be transmitted simultaneously within the same licensed band. Such systems are typically referred to as in-band on-channel (IBOC) DAB systems, and are being developed for both the FM and AM radio bands. In order to prevent significant distortion in conventional analog FM receivers, the digital signal in a typical FM-IBOC DAB system is, e.g., transmitted in two sidebands, one on either side of the analog FM host signal.
Despite the above-noted advances in the development of DAB systems for the delivery of CD-quality audio, a given user that may have already listened to a given piece of music several times, e.g., using an FM receiver, is nonetheless required to go through the process of downloading the entire piece over the Internet in order to purchase that piece of music. A need therefore exists for a more efficient process of delivering purchased music and other types of information to authorized users.